Mozilla and all their projects just plain flat out kick ass. Firefox and Thunderbird are both excellent and getting better all the time. Ability to customize both to suit your own needs is a huge plus. The developer community Mozilla is supporting and encouraging around their projects is a leading example of the value of open source software. You can learn a lot here, if you choose, or you can just download the latest versions of Firefox and Thunderbird and be on your way.
As for safety on the WWW, you can, if you choose, lock Firefox down tight with the built in options for privacy and security and, with the judicious use of add-ons make it even more so. Additionally, Firefox developers respond quickly to newly discovered vulnerabilities with security updates as needed.
I love this browser, but I don't know what is wrong with these guys who released ver. 4, it is very bad now .. it's true they are adding a lot of good features BUT the most important thing for anyone of us is the software stability !!!!
Firefox ver 4 crashes many time whenever I have many tabs opened, even sometimes it crashes on a simple one or two tabs opened.
this is very annoying.